The present invention relates to a method of three-dimensional wire alignment and an apparatus therefor for manufacturing a wire structure wherein the wire is aligned three-dimensionally at prescribed pitches, and also to a method of manufacturing electrically conductive materials such as printed circuit board materials or anisotropic conductive materials using the wire structure.
Manufacturing wire structures wherein electrically conductive wires are aligned three dimensionally and accurately at prescribed pitches is an important technology for manufacturing an anisotropic conductive material comprising a wire structure embedded into rubber or resins. Anisotropic conductive materials are used as members for printed circuit board materials or the like wherein the electrodes on a device and on a distributing board are connected facing with respect to each other. In this case, electricity is conducted only between electrodes along the wires, and is insulated in the direction horizontally of the device or the distributing board. By taking advantage of such characteristics, anisotropic conductive materials have been widely used as wiring members for calculators, liquid crystal devices, and so on.
The printed circuit board includes a slot for receiving an integrated circuit and a group of connecting terminals for variety of electronic components on one side, and a printed conductive path for connecting components on the other side, which has been traditionally used in quantity as a constituent member for electronic equipment.
Conventionally, materials used for printed circuit boards have been manufactured by the steps of manufacturing a plate body made of insulating materials such as epoxy resin or glass, forming a through hole for conduction of electricity at a prescribed location by drilling operation, coating the through hole for conduction of electricity with a conductive metal such as copper by means of plating operation, and then sealing the through hole with a sealing agent.
However, there are recognized disadvantages in that drilling on the plate body produces chips during the process, which may lead to product defects, and that plating is subject to cracks at the edge portion of the board material, which may lead to faulty conductivity. In addition, the ratio of the length of the through hole (thickness of the board) to the diameter of the hole is limited to about 5 for drilling, and therefore, the lower limit of diameters of through holes for boards of 1 mm in thickness will be about 0.2 mm. However, smaller diameters are preferable for obtaining a printed circuit board of high densities, which has been difficult to obtain by drilling.
A circuit board manufactured using the steps of inserting electric wires, such as Ni or Co, into a frame body, pouring an insulating material such as molten epoxy resin or the like therein, cutting it along a plane perpendicular to the metal wires after the resin is hardened, and connecting both cut planes electrically is presented (see Japanese Unexamined Patent Application Publication No. 49-8759).
However, since an epoxy resin or the like is used in this circuit board, there has been a disadvantage in that accuracy in dimension such as a pitch of the through holes may be impaired due to volumetric shrinkage of about 2 to 3% in the process of the curing of the resin. This is a serious disadvantage since accuracy in dimension is a very important factor in a high-density printed circuit board.
In addition, in this type of circuit board, a difference of the thermal expansion between the circuit board material and conductive layers laminated on one or both sides thereof (photo process layer) is not considered, and thus, separation between board materials and conductive layers may occur due to the impact applied during service or temperature variations. Separation may also occur between an insulating material and the metal wires.
In view of above described disadvantages of the prior art, it is an object of the present invention to provide a method of three-dimensional wire alignment and an apparatus used therefor that enables manufacturing of large size wire structures as well as miniature wire structures wherein a wire is aligned three-dimensionally accurately at prescribed pitches, and that ensures high productivity and facility of handling.
It is another object of the present invention to provide a method of manufacturing conductive materials such as a printed circuit board material or an anisotropic conductive material wherein satisfactory electrical conductivity is established and the thermal expansion property may be controlled so that separation between a board material and a conductive layer, and between an insulating material and a metallic line (wire) during service can be prevented.
It is still another object of the present invention to provide a method of manufacturing conductive materials that enables the realization of a printed circuit board material or an anisotropic conductive material with higher density and improved dimensional accuracy conveniently and easily with improved workability.
According to the present invention, there is provided a first method for manufacturing a wire structure having a wire aligned three-dimensionally at prescribed pitches comprising the steps of disposing one or more frame bodies, which have a prescribed thickness, peripherally of a rotary shaft. Winding wires on the frame bodies at prescribed pitches in such a manner that the wire contacts at least one surface of the frame bodies by rotating the rotary shaft; and repeating steps of stacking another frame body on the above described frame bodies and winding wires thereon at prescribed pitches.
According to the present invention, there is also provided a second method for manufacturing a wire structure having a wire aligned three-dimensionally at prescribed pitches comprising the steps of disposing two separator plates, each having a prescribed thickness, at positions parallel to and spaced from a rotation axis of a rotary shaft. The wires are wound on the separator plates at prescribed pitches by rotating the rotary shaft about the rotation axis; and repeating steps of stacking subsequent sets of separator plates on the above described two separator plates and winding wires thereon at prescribed pitches.
According to the present invention, there is further provided a third method for manufacturing wire structures having wires aligned three-dimensionally at prescribed pitches comprising the steps of building a mold, either by disposing one or more frame bodies having a prescribed thickness on the periphery of the mold or by disposing two separator plates having a prescribed thickness on any one or two sides of the periphery of the mold, keeping a prescribed distance apart from one another. The wires are wound at prescribed pitches on the above described frame bodies or the separator plates building the mold by moving a wire bobbin around the mold, and repeating steps of stacking subsequent sets of frame bodies or separator plates on the above described frame bodies or the separator plates and winding a wire thereon at prescribed pitches.
According to the present invention, there is also provided a first apparatus for three-dimensional wire alignment comprising two side plates spaced apart and facing one another disposed along a direction perpendicular to a rotation axis of a rotary shaft defined therein. Two separator plates each having a prescribed thickness, are disposed at positions parallel to and spaced from the rotation axis. The apparatus also includes a driving means for rotating the side plates and separator plates about the rotation axis; and a wire bobbin for feeding a wire to be wound thereon at prescribed pitches from the side of the outer periphery of the two separator plates.
Preferably, in the above described method and apparatus for three-dimensional wire alignment, V-shaped grooves are formed on an end surface of the separator plates at prescribed pitches for aligning wire three-dimensionally and accurately.
According to the present invention, there is provided a second apparatus for three-dimensional wire alignment comprising a wire feeding mechanism, a spacer and a guide block for straining a wire, a mold for fixing the spacer and the guide block, and a rotary mechanism for rotating the mold. Groove portions for disposing the wire on the spacer are formed at prescribed pitches and prescribed depths, and guide blocks are provided with notched portions, at prescribed pitches, for defining the position of the wire and supporting the tensile strength of the wire.
Preferably, this apparatus for three-dimensional wire alignment is constructed in such a manner that as the spacers and the guide blocks are subsequently stacked, the distance between the spacer and the notches formed on the guide blocks becomes larger. It is also preferable that the apparatus is constructed in such a manner that the wire is strained between a plurality of groove portions positioned on an imaginary line extending almost straightly parallel with the stacking direction of the spacers and notched portions formed on the guide block when the spacers are stacked in the prescribed multiple layers.
It is also preferable that the guide block is provided with a bevel portion corresponding to the straining angle of the wire. The bevel portion prevents contact between the wire strained from the guide block and portions of the guide block other than the notched portions. It is further preferable to form the bottom portion of the notched portion in a profile having an obtuse angle or a curvature because it can prevent the wire from being broken due to extreme bending thereof.
When straining a wire, it is preferable to use a wire feeding mechanism that can control the wire feeding position by sliding itself in a direction parallel to the rotary shaft of the rotary mechanism, and therefore, a plurality of wires may be fed to the mold at one time. In order to achieve high productivity, it is preferred to use a mold having a symmetric structure about the rotary shaft of the rotary mechanism.
According to the present invention, there is provided a method for manufacturing a wire structure wherein the wire is strained three-dimensionally at prescribed pitches between groove portions and at pitches of the thickness of a spacer comprising steps of: using a wire feeding mechanism; a spacer provided with grooves formed at prescribed pitches and at prescribed depths for straining the wire by arranging it at prescribed pitches; a guide block provided with notched portions formed at prescribed pitches for defining the straining position of the wire and supporting the tensile strength of the wire; a mold for mounting the spacer and the guide block; and a rotary mechanism for rotating the mold; rotating the mold while adjusting the feeding position of the wire from the wire feeding mechanism so that the wire is received in the prescribed notched portions and the groove portions; and stacking the spacers and the guide blocks on the mold while suspending the rotation of the mold instantaneously.
Preferably, the guide block is disposed in such a manner so as to lessen the stress that is due to the tensile strength of the wire applied to the edge portion of the spacer to prevent the deformation of the spacer so that the accuracy of the position where the spacers are stacked is ensured.
According to the present invention, there is further provided a method for manufacturing a conductive material comprising the steps of: pouring an insulating material into a wire structure obtained by any one of the above described first to third methods of three-dimensional wire alignment or method of manufacturing the wire structure; curing the insulating material, and slicing the cured insulating material along the planes traversing the wire.
Preferably, the insulating material is any one of rubber, plastic, or plastic-ceramics composites.